It’s a worst-case scenario, the kind of story that makes people’s blood boil.

Allie Phillips heard it as a shelter volunteer in Michigan in the early 2000s, when she spoke to a family that had gone on vacation for 10 days, leaving its dog with a pet sitter. The sitter let the dog out into a fenced backyard to play, but it somehow escaped and ended up at an animal shelter in the next county. Before the family returned from vacation, Phillips says, the dog had been sold to a Class B dealer—an animal broker collecting dogs and cats for use in experimentation.

Given that animal shelters have a mission of protection, how could this have happened?

It likely happened due to the practice of pound seizure, which animal welfare advocates have been battling for years.